As part of the fundraising campaign – from February 10 to 16 – local schools and youth groups, such as the Brownies and Scouts, are being invited to wear their onesies for the day in exchange for a donation to the Hastingwood-based Hospice.

Last year, Thorn Grove Primary in Bishop’s Stortford was one of the first schools to sign up, raising almost £200 for St Clare.

Headteacher Philippa Roy-Chowdhury said: “The children absolutely loved taking part in Onesie Week and all looked brilliant coming to school in their all-in-ones.

“It was an ideal way to engage them in charity giving in a fun way and to support a local good cause making a real difference to the lives of people in our community.”

In addition to wearing their onesies, organisers are encouraging participants to come up with other fundraising ideas, such as holding a onesie disco or film night.

To take part in Onesie Week, call the St Clare fundraising team on 01279 773750 or e-mail fund@stclarehospice.org.uk.